NIIMBUS ULTIMATE Series User manual

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HEADPHONE AMPLIFIER
NIIMBUS ULTIMATE SERIES
HPA US 4+
USER´s MANUAL

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Content
Theme Page
About NIIMBUS 4
Safety Instructions 5
The Earth / Grounding Concept 6
Connection / Connectors 8
General 9
Remote Control 11
Block Circuitry 12
Operation 13
About PRE-GAIN 14 / 16
Software 21
Things to know 22
Disposal 25
Technical Data 26
Dismantling 27
Jumper Settings 28
Conformity Statement 30
Warranty 31
CAUTION !!
THE HIGH OUTPUT LEVELS ACHIEVABLE
WITH THIS UNIT MAY
DAMAGE YOUR HEARING OR THE HEADPHONES
IF OPERATED CARELESSLY !!

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Cordial thanks for your decision in favour of a product !
is a trademark and product line of Lake People electronic GmbH. Lake People electronic
GmbH develops, manufactures and distributes products in the professional range, for broadcast,
television, airports, exhibition halls, festival venues, theatres, large-scale installations, private studios and
more. In the private sector as well, Lake People products become increasingly popular due to their
outstanding quality.
The trademark and product line is specially intended to supply the Hi-Fi and High-End market
with its specific requirements.
Who develops equipment ?
devices are exclusively developed in Germany by the engineers of Lake People electronic
GmbH. In doing so, the team of developers can draw on over thirty years of experience and countless
products for the pro-audio domain.
Among others, the first German-made 20-bit A/D and D/A converters were developed by Lake People in
the early nineties of the past century.
Who manufactures equipment ?
devices are exclusively manufactured in Germany by Lake People electronic GmbH or
contractors in the company's vicinity.
Lake People - and by association - put high emphasis on domestic manufacturing. As well, all
component suppliers are chosen in order to achieve the main part of added value inland.
How do devices get to the customer ?
devices can be obtained from respective specialist suppliers. If there is none such accessible
regionally, the customer is supported by transregional distribution partners (google may help...) and, of
course, by on-line shop.
…and if it doesn't work like it should ?
devices are covered by a 5-years warranty. In case of any malfunction during this period, they
can be shipped to the manufacturer directly. Of course, the client will benefit from full technical
support even when warranty has expired. Any technical questions or need for advice is welcome.
is a subsidiary of
LAKE PEOPLE electronic GmbH
Turmstrasse 7a
D-78467 Konstanz
Fon [phone]
Fax [phone]
www.lake-people.de
www.lake-people.com
www.NIIMBUS-audio.de
www.NIIMBUS-audio.com
www.violectric.de
www.violectric.com

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General Safety Instructions
WARNING
For your protection, please read the following:
Water, Liquids, Moisture:
This appliance should not be used near water or other sources of liquids.
Care should be taken so that objects do not fall and liquids are not spilled into the enclosure through
openings.
Power Sources:
The appliance should be connected to a power supply only of the type described in the operating
instructions or as marked on the appliance.
Grounding:
Care should be taken that this appliance is operated with proper grounding only.
Power Cord:
Power supply cords should be routed so that they are not likely to be walked on or pinched by items
placed upon or against them, paying particular attention to cords at plugs, convenience receptacles, and
the point where they exit from the appliance.
This unit is equipped with a 3-pole mains cable with German 3-pin mains plug.
In some countries this unit must be operated with a mains adaptor, supplied by the owner.
Please refer to the table below to connect a mains plug:
OVERVIEW: POWER C
ORD FUNCTION AND COLORS
CONDUCTOR COLOR Alternativ
LLIVE BROWN BLACK
NNEUTRAL BLUE WHITE
E PROTECTIVE EARTH GREEN+YELLOW GREEN
U.K. Mains Plug Warning:
A moulded mains plug that has been cut off from the cord is unsafe.
Discard the mains plug at a suitable disposal facility.
NEVER UNDER ANY CIRCUMSTANCES SHOULD YOU INSERT A DAMAGED OR CUT MAINS PLUG
INTO A 13 AMP POWER SOCKET. Do not use the mains plug without the fuse cover in place.
Replacement fuse covers can be obtained from your local retailer.
Replacement fuses are 13 amps and MUST be ASTA approved to BS 1362.
Mains Fuse:
The mains fuse of this appliance is soldered in place and accessible from the inside only!!
A blown fuse may indicate an internal problem and should be replaced during qualified servicing or repair
work !!
Switchable Power Supply:
Connect this unit to the power source indicated on the equipment rear panel only to ensure
safe operation !!
This unit is provided with an internally settable mains supply for 115 / 230 V AC.

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Service / Repair:
To reduce the risk of fire or electric shock, the user should not attempt to service the appliance beyond the
measures described in the operating manual. All other servicing or repair should be referred to qualified
personnel !!
Electromagnetic Compatibility
This unit conforms to the Product Specifications noted as Declaration of Conformity at the end of this
manual. Operation is subject to the following conditions:
- this device may not cause harmful interferences
- this device must accept any interference received,
including interference that may cause undesired operation
- this device must not be operated within significant electromagnetic field
The Earth / Grounding Concept
VOR DEM ÖFFNEN NETZSTECKER
ZIEHEN!! PULL MAINS BEFORE
OPENING!! AVANT D´OUVRIER
RETIREZ LA FICHE MALE!!

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General GROUND-LIFT Jumper ( accessible from the inside.
Mind the SECURITY INSTRUCTIONS !! ):
Ex-works this jumper is set to the LIFT position.
The internal ground potential is “lifted”by means of this jumper.
As a result, the interconnection for DC voltages and lower frequencies (< 150 Hz) will be cut. Higher
frequencies will be bled off to earth potential through the RC filter. The LIFT position is helpfulin case of
hum or jitter caused by different ground/earth potentials.
Of coarse full electrical protection is granted as the case is always connected to ground/earth potential !
See page 28 / 29 "Jumper Settings" for details.
Unfortunately there is no general recommendation how to solve hum and jitter problems - or even
minimize them. The best way to succeed is to check different options !! In case of balanced cables, it
should always been verified if the shield of the cable is connected to the shell of the XLR connector. The
shell is ALWAYS connected to earth potential when the connector is inserted !!
Concerning ANALOG inputs and outputs, the relationship between ground and earth may be modified.
Electrical safety is always ensured, since the earth conductor is permanently ‘
connected to the enclosure !!
XLR GROUD-LIFT Jumper
( Accessible from the inside. Mind the SECURITY INSTRUCTIONS !! ):
G(ROUND): Ex-works all jumpers are set to "G" (ground) position.
Pin 1 is connected to the internal ground reference.
High frequency interference is deflected to the case via a 100 nF capacitor.
L(IFT): The interconnection between Pin 1 and ground is open. High frequency interference is
deflected to the case via a 100 nF capacitor. This jumper position is specifically useful
if the unit is equipped with audio-transformers !!
C(ASE): Pin 1 is connected to the case, the 100 nF capacitor is bridged. This jumper position may
be varied together with the General GROUND-LIFT jumper.
Please note that with jumpers not in the ex-works position
EMC emission might occur,
for which the user is responsible only !
So, only change these settings when you know what you are doing !!

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Connection / Connectors for Analog Signals

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GENERAL INFORMATION
The NIIMBUS HPA US 4+ is a stereophonic headphone amplifier designed to drive low-, medium- and
high-Z loads (16...600 ohms) as usually represented by high-quality headphones.
Because of its four built in amplifiers and the 4-pin XLR socket on the front it is also best suited to connect
balanced headphones.
Due to its specific, highly variable, low-noise and low distortion circuit design especially optimised for
dynamic and orthodynamic headphones, the NIIMBUS HPA US 4+ fulfils even highest demands.
Features:
-1 x stereo balanced inputs with gold-plated Neutrik XLR connectors
-2 x stereo unbalanced inputs with gold-plated full metal premium RCA connectors
-All three inputs selectable on the front panel
-PRE-GAIN = switchable input gain in eight steps -15/-12/-6/0/+6/+12/+18/+24 dBr
-Balanced and unbalanced stereo line outputs with RCA resp. XLR sockets,
gold plated, pre-post fader assignable
-Independent channel design
-Volume control with 256 steps of 0.4 dB through reed relay attenuator
-Balance control
-Remote controlled and motorized volume control, input/output selection, mute
-High-Quality op-amps in the signal path
-High-quality MKP capacitors in the signal path
-0.1 and 1% metal film resistors throughout the unit
- 4 Discrete-design power amps with 8 transistors per channel
-Output management: headphones active / line-out active / both active / none active (mute)
-2 x 6.3 mm (1/4”) silver-plated Neutrik headphone outputs
-1 x 4-pin XLR socket, gold plated for balanced headphones
-delayed relay-based headphone output during power on / instant cut-off for power off
-2 x toroidal transformers, 25 + 25 W
-Large filtering capacitors in the power supply (> 50.000 uF)
-Switchable ground lift
-Rugged steel case with metallic coating
-Solid, 10 mm aluminium front panel
With its dimensions, the NIIMBUS HPA US 4+ ensures optimum flexibility combined with high output
power. During design, high emphasis was put on operational safety even when the unit is operated
inappropriately.
The NIIMBUS HPA US 4+ is equipped with safety circuitry and internal filters to prevent damage to the
connected headphones due to DC voltages at the outputs, overload, over temperature and high-
frequency overload beyond the audible range.
THE CASE
of NIIMBUS HPA US4+ is made of 2 mm sheet steel and a thick 10 mm aluminium front panel.
This choice of material ensures high mechanical stability and resistance whilst maintaining a high
optical and haptic quality.

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GROUND AND PROTECTIVE EARTH
The case of NIIMBUS HPA US 4+ is connected to protective earth.
POWER SUPPLY
Mains power is provided via a three-pin IEC/CEE socket and mating "cold-appliance" mains cord with
Schuko-type plug for units purchased in middle Europe.
The device is set to 230V mains, whereas the actual voltage may vary between 190 and 240 volts for
flawless operation.
The mains voltage may be altered to 115 V AC supply inside the unit with the aid of a mains voltage
selector. In this case stable operation is granted in a range of 85 to 120 V (see page 32).
Two toroidal transformers each with 25 Watt are providing the internal operating voltages of +/-30 V. Out
of these voltages some more operating voltages are generated.
MAINS FUSE
The 0.25A time-lag fuse is soldered in place on the circuit board. In case, it must be replaced with a fuse
of the same type only.
CAUTION !!
MIND THE SAFETY INSTRUCTIONS:
A blown fuse indicates an internal fault and
should be replaced during qualified repair or
servicing only !!

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THE REMOTE CONTROL FOR NIIMBUS HPA US 4+
Function
This remote control sends out infrared rays.
For that purpose there is a infrared LED on the front.
The remote control should point in direction of the target device to
obtain best functionality.
The operating distance is about 5 - 7 meters (15 –20 ft).
With the “Volume +“and “Volume -“buttons the volume of NIMBUS
HPA US 4+ can be altered. This is done with a motor inside the amp
to get the volume knob into motion.
With the “Mute“button the internal mute function is engaged.
A direct “Mute“can only be released by the remote control.
With the “Input 1 / 2 / 3“buttons one of the three inputs may be selected.
With the “Line-Output“and “Head-Output“buttons you can control
whether the front panel headphone outputs are active or the back
mounted line outputs –or both !
(pictures show the original size of the remote control)
Maintenance
The remote control is powered by a little “CR2032“size lithium battery.
The battery diameter is 20 mm, the hight is 3,2 mm –that´s where the
name comes from.
If you share the opinion that the battery is empty you may check this with
the aid of your smartphone. The camera function reacts on the infrared
rays of the remote control with cannot be seen with human eyes.
So just point the remote control to the camera of your smart phone and
press a button. When you don´t see any action the battery is empty.
Take a paperclip or something similar and bend it like indicated on the
back of the remote control. Plug it in the little hole to force the keypad to
come out the aluminium frame –it is held by magnets.
Now you can carefully take off the electronics to replace the battery.
The (-) pole must point to the PCB.
The (+) pole is the wider part and normally denoted.
It has to point “upwards”.
Re-assemble the keypad, take care of the infrared LED !

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Block circuitry NIIMBUS HPA US 4+

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THE POWER-SWITCH The unit is put into operation by means of the power
switch.
Power-on status is indicated by the white “ON”LED.
The power-on procedure takes about 5 seconds.
During this time the “STATUS”LED is red and turns
white when all internal parameter checked.
Also the LED of the last selected input is flashing and
the outputs are muted.
Always the last setting is recalled.
THE SIGNAL INPUTS
THE BALANCED SIGNAL INPUTS
are situated on the rear panel of the unit and are labelled as "BAL IN (1) LEFT" and "BAL IN (1) RIGHT".
They are fitted with gold plated XLR sockets from Neutrik.
Input impedance is 10 kohms.
Maximum input level should not exceed +21 dBu.
Please note:
Unbalanced signals can be injected as well by means of an adaptor.
Also see page nn.
THE UNBALANCED INPUTS
For the use with unbalanced signals, gold plated full metal premium RCA sockets are provided.
They are labelled as "UNBAL IN LEFT" and "UNBAL IN RIGHT" “2”and “3”.
Input impedance for these inputs is 10 kohms.
Maximum input level should not exceed +21 dBu.
This value is reduced to +15/+9 dBu if PRE-GAIN is set to +6/+12 dB or higher !!
Balanced XLR
pin-out:
PIN 1 GND
PIN 2 (+) PHASE
PIN 3 (-) PHASE

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INPUT PRE-GAIN
These DIP-switches are situated on the back of the unit inside the field of the analogue inputs.
Settings can be made for the left and right channel, they shall not be different from each other.
With these switches an additional gain or attenuation may be set.
It is dependent on the output level of the input source and the sensitivity of the headphones connected.
By this measure it is maintained to achieve lowest possible noise and maximum travel of the volume
attenuator. The high gain/attenuation range of about 40 dB ensures a perfect match of any source with
any headphone in the market.
Please see page 16 to learn more about: “Too loud ? Too soft ? The PRE-GAIN method”
SELECTING / ACTIVATING AN INPUT
With the “1 - XLR / 2 - RCA / 3 - RCA“buttons on the front panel of NIIMBUS HPA US 4+ one of three
analogue inputs can be activated. The corresponding LED is illuminated.
You can also use your remote control for this purpose:
Press “INPUT 1“on the remote control for input 1 - XLR
Press “INPUT 2“on the remote control for input 2 - RCA
Press “INPUT 3“on the remote control for input 3 - RCA

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THE VOLUME ATTENUATOR
is to set the desired volume for the left and right channel simultaneously.
Volume can also be set via your remote control. For this purpose, the volume control is actuated by a
servo motor. Manual operation of the knob at the same time is possible without the risk of damage
(although not useful…).
Press the “Volume + / -”button on the remote control in order to increase or decrease volume.
The volume attenuator itself is very special.
Attenuation is made in 256 step of 0.4 dB each. The steps are switched with special “reed relays”.
Here, the switching contacts are situated in a glass tube filled with a protective gas.
The contacts are actuated by a magnetic field.
BALANCE CONTROL
is provided to compensate moderate level differences between left and right channel. These may root in
the recorded material itself, noticeable differences between left and right headphone system, or
differences in the user’s individual hearing.
All of the above can be carefully compensated.
The balance control offers a precise center detent in case no adjustment is necessary. In order not to
impair the perfect crosstalk specs of HPA US 4+, it takes effect on the right channel only.
THE AMPLIFIER(S)
The input signals are fed to an amplifier stage especially designed for this application, with eight
transistors per channel. The HPA US 4+ houses no less than four of those ! Channels are physically
separated from each other to ensure optimum crosstalk rejection.
The frequency range covers 5 Hz ... 250 kHz (-0.5 dB) in order to ensure fully linear performance within
the entire audible range. Overall gain is set to -4 dB (unbalanced) or +2 dB resp. (balanced) to ensure
lowest self generated noise.

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Too loud ? Too soft ? The PRE-GAIN method
The NIIMBUS HPA US 4+ is specially designed to drive headphones. To do so it is placed between up to
three sources and the headphones. Headphones however can present load impedances from 8 to 2000
ohms and efficiency ratios from 85 to 115 dB per Milliwatt. The sources may have output levels between
0.5 Volt up to 10 Volt. Thus it can be quite tricky to fulfil all demands, since...
…owners of high-efficiency headphones will rarely set the volume control higher
than 9 o'clock in order to exclude hearing damage, while
... the maximum setting may still be too soft for low-efficiency headphones, but
…all users expect highest quality at lowest noise and distortion.
Thus, the circuitry must adapt itself as the headphone won't !
WE CALL THE SOLUTION TO THIS PROBLEM PRE-GAIN
A single amp of NIIMBUS HPA US 4+ has no gain but an attenuation of -4 dB (about 60 % of the input
signal). In case a balanced headphone is connected two amps are active with a combined gain of +2 dB
(about 140 % of the input signal).
By this measure the amps will produce an extremely low self-generated noise which can hardly been
heard even with highest sensitive in-ear-monitors (IEM).
On the other hand the very powerful amps of HPA US 4+ with their high operating voltage are able to
drive low efficiency or high impedance headphone to the full with easel. You will be unable to find a
headphone which cannot easily be driven by HPA US 4+. This effortless action will save your precious
headphones as they will never see a distorted signal from the amp.
The alignment between amplifier and headphone is provided by the preamp stage, which can boost or
attenuate the input signal in eight steps of -15 / -12 / -6 / 0 / +6 / +12 / +18 / +24 dBr. For this purpose,
two switching devices are located on the rear panel for left and right channel individually.
HOW TO OPTIMIZE THE PRE-GAIN SETTING:
Connect your source to NIIMBUS HPA US 4+ and plug in your headphone.
Listen !!
Your amp is adjusted best by the individual PRE-GAIN setting when the volume control for “normal”
listening is positioned around 12 o´clock.
So it is provided that there is enough attenuator travel to boost the signal through lower level
passages or to listen with higher volume.
On the other hand the attenuator travel is optimized to reduce the self-generated noise from the amp.
In case you cannot reach the 12 o´clock position because the input signal is too loud, feel free to reduce
the signal with the PRE-GAIN steps -6 / -12 / -15 dBr.
In case the signal is too soft even with volume settings above 12 o´clock please use the PRE-GAIN
settings +6 / +12 / +18 / +24 dB to achieve more gain.
CAUTION !!
To avoid unwanted level leaps the settings should be altered under the following conditions only:
-The unit should –but must not - be switched OFF
-the "VOLUME" control should be set to minimum
-left and right channel settings should be the same
-avoid to increase the setting by more than ONE step above
Ex-factory, all switches are set to their lowest position - i.e. 0 dB PRE-GAIN - which should be sufficient
for most applications.

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THE INPUT PRE-GAIN SETTINGS
Ex works all switches are set to the lower position.
Ex works setting
So, if you share the opinion that your amp could act a bit softer you may set the “-6 dB”and or “-12 dB”
dip switches to “ON”position. Both switches “ON”mean “-15 dB”.
If your amp should have more juice take the positive levels into account from “+6 dB”, meaning double
gain, up to “+24 dB“, meaning sixteen-fold gain.
Other that the above shown switch positions are senseless but harmless.
DE- / ACTIVATING THE HEADPHONE OUTPUTS:
Pressing the "PHONES OUT" button will activate or deactivate the headphone outputs.
The white LED shows the activated state.
The red LED shows the deactivated state.
This procedure is also maintained by the “OUTPUT / HEAD”button of the remote control.

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DE- / ACTIVATING THE LINE OUTPUTS:
Pressing the "LINE OUT" button on the front panel will activate or deactivate the line outputs situated on
the back panel.
The white LED shows the activated state.
The red LED shows the deactivated state.
This procedure is also maintained by the “OUTPUT / LINE”button of the remote control.
HINT:
When the "MUTE“Button of the remote control is pressed, all outputs from HPA US 4+ are muted, this
concerns the back mounted line outputs and the front mounted headphone outputs.
The front LEDs from "PHONES OUT“and "LINE OUT“are red now.
The mute may be deactivated separately for the headphones outputs or the line outputs by pressing the
dedicated button on the front panel or on the remote control.
For both ways simultaneously the mute may be released by pressing the “MUTE”button on the remote
control again.
THE BALANCED HEADPHONE OUTPUT
NIIMBUS HPA US 4+
offers a dedicated headphone output
to connect balanced headphones.
The output is situated on the front
panel and comes as a gold plated
4-pin XLR socket.
UNBALANCED HEADPHONE OUTPUTS
The NIMBUS HPA US 4+ offers two stereophonic headphone
outputs, each equipped with a 6.3mm (1/4") jack socket.
Because HPA US 4+ has a 4 channel amplifier (2 x stereo),
each socket is driven by a dedicated stereo amplifier
Please note:
The RIGHT phone jack is connected to the in-phase stereo signal,
whereas the left phone jack is connected to the 1800phase shifted signal.
HINT:
To protect the headphones the outputs are cut during powering on. This procedure takes about five
seconds. When powering off the outputs are cut instantly.
Balanced Headphone Socket Pin-Out:
Pin 1 (+) Left channel
Pin 2 (-) Left channel
Pin 3 (+) Right channel
Pin 4 (-) Right channel
Unbalanced Headphone
Socket Pin-Out:
TIP Left channel
RING Right channel
SLEEVE GND

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THE LINE OUTPUTS
THE UNBALANCED LINE OUTPUTS
are located on the rear panel of the unit and are marked as “UNBAL OUT LEFT”and “UNBAL OUT
RIGHT”. Gold-plated full metall premium RCA connectors are implemented here.
THE BALANCED LINE OUTPUTS
are located on the rear panel of the unit and are marked as “BAL OUT LEFT”and “BAL OUT RIGHT”.
Gold-plated XLR connectors are implemented here.
Hint:
With a balanced-to-unbalanced adapter this connection may also be used for unbalanced cables.
PLEASE NOTE THAT IN THIS CASE PIN 3 HAS TO BE LEFT OPEN !
OUTPUT GAIN SETTINGS
The level of the activated input will appear unaltered at the line outputs.
This level may be adapted by the "OUTPUT GAIN" dip-switches in order to perfectly match the
subsequent equipment.
The setting is similar to the “PRE-GAIN”setting described earlier on page 17.
The combined setting of the “+12 dB”and “+6 dB”switches will result in +15 dB gain.
The combined setting of the “-12 dB”and “-6 dB”switches will result in -15 dB gain.
Please note that output level at the unbalanced output is generally -6 dB lower compared to the
balanced output.
Balanced Interconnection
of the XLR Socket: Unbalanced Interconnection of the XLR Socket:
PIN 1 GND PIN 1 GND
PIN 2 in PHASE PIN 2 Signal
PIN 3 out of PHASE PIN 3 OPEN !!

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PRE / POST FADER or FIXED-VARIABLE
The line out signal may be sourced from two different positions inside NIIMBUS UHPA US 4+.
If you want to use the activated input signal as is, maybe to source a unit with its own attenuator or a
recording device, than the “FIXED OUT”or “PRE-FADER”mode is the right choice.
Here, the input signal is routed directly to the line outputs without any alteration from the volume
attenuator. Of course you may alter the output level by using the line-out dip-switches.
If you like to operate you NIIMBUS HPA US 4+ as pre-amp device of outstanding quality to drive some
active speakers or power amps, than “VARIABLE OUT”or “POST-FADER”is the weapon of choice.
Now, the line out signal is attenuated by the volume control of NIIMBUS HPA US 4+.
Feel free to adapt the output level by using the line-out dip-switches to optimize the attenuator travel.
Signal processing inside NIIMBUS HPA US 4+ is always unbalanced. This is no disadvantage as the
so called “fully balanced”signal processing often generates more issues that solving them.
Further, only this method is capable to use the device also as a converter between unbalanced and
balanced signals.
With you NIIMBUS HPA US 4+ you are able to feed an unbalanced signal and to listen with your
balanced or single ended headphones. Also you can feed subsequent devices from the unbalanced
and / or balanced line outputs.
You may also feed a balanced signal and listen to it with your balanced or single ended headphones.
Simultaneously you may again use the unbalanced and / or balanced line outputs.
SWITCHING BETWEEN PRE / POST FADER
is accomplished by software:
Pushing long ( > 2 seconds ) the "3 - RCA" button will force the assigned white LED to flash.
The current state is displayed by the illuminated "PHONES OUT" LED = "Pre-Fader" or "LINE OUT"
LED = "Post-Fader". Pushing the dedicated button will alter the state.
To end the procedure press again ( > 2 seconds ) the "3 - RCA" button, the white LED will stop flashing.
Ex works the unit is set to "Post Fader" operation.
ERROR REPORTING:
To ensure error-free operation and not to harm your valuable headphones in a comprehensive way your
NIIMBUS HPA US 4+ is equipped with a number of protective circuits:
-During powering there is a five seconds delay to protect your headphones from possibly
unwholesome noises. After the time the headphone outputs are switched to theamp.
Also the instant cut-off after powering off is intended to protect your headphones.
-DC voltages are no good part of the output signal and must be avoided. If such are detected, the
headphone sockets are cut from the electronics and the status LED is switched to red. When the DC
voltage has vanished the amp will automatically return to “normal”operation.
-Overload causes distorted output signals and are also harmful for the headphones. If an overload
was detected, the headphone sockets are cut from the electronics and the status LED is switched to
red. When the overload disappeared, the amp will automatically return to “normal”operation.
-All errors will also reset when the unit is switched off and on again.
In case that there is still an error condition the protecting circuits will keep the error mode and the
status LED is red.